Question

x/x-4 - 4/x-5=- 4/x^-9x +20

Answer 1

by the looks of this, I bet you meant:

x/(x-4) - 4/(x-5)=- 4/(x^-9x +20)

x/(x-4) - 4(x-5) = 4/( (x-4)(x-5) )

Major hint:
what would happen if I multiplied each of the three terms by (x-4)(x-5) ??

Give it a try, it becomes very easy.